Abstract: Correct and consistent contraceptive use is highly effective at preventing unintentional pregnancies, and condom use reduces the risk of acquiring sexually transmitted infections. Despite the availability of condoms and contraceptives in the United States (U.S.), 95% of unintended pregnancies are associated with contraceptive non-use or incorrect/inconsistent use, and nearly 20 million new cases of sexually transmitted infections occur annually. Prior research has demonstrated the importance of the context within which sexual behavior takes place to an individual?s condom/contraceptive use. Given reported changes in sexual frequency and sexual repertoire (i.e. the range of sexual behaviors reported in a sexual event or over a particular timeframe) in recent years, an updated and more detailed assessment of sexual behaviors in relation to condom/contraceptive use is warranted. The National Survey of Sexual Health and Behavior (NSSHB), a national probability survey of adults and adolescents in the U.S., has detailed data on both sexual behaviors and contraceptive/condom use from 2009 to 2018 and therefore serves as a unique dataset to address these questions. Among 14- to 49- year old individuals from the NSSHB dataset, we aim to (1) assess frequency of past-year as well as past-year sexual repertoire in 2009 versus 2018; (2) evaluate how frequency of intercourse in the past year is related to event-level condom/contraceptive use; and (3) evaluate how past-year sexual repertoire affects past 6- month condom/contraceptive use.